The aim of these research efforts is to explore the psychobiology of cognition in man. Studies are carried out that would help define the psychobiological determinants of components of cognition that are necessary for learning, memory, and related mental functions. Studies have explored the specific and discrete mechanisms which account for the acquisition, processing, encoding, consolidation, and retrieval of experience. Clinical studies are developed programmatically to further our understanding of the biological and psychological determinants of impaired cognition in psychiatric and neuropsychiatric patients. Understanding the central nervous system effects of drugs of abuse in terms of their cognitive expression represents another important research direction that is presently underway. Aspects of state-dependent learning and retrieval of the discriminative properties of drugs, affect and cognition and the role of the reward system in cognition are all presently being studied. Specific forms of central nervous system dysfunctions (e.g., as defined by type of lesion in neuropsychiatric disorders) may affect distinct components of cognitive processing. Similarly, psychoactive drugs that affect discrete aggregates of neurons, may alter different aspects of cognition and information processing and serve to model forms of cognitive dysfunctions in man. Based on empirical studies of clinical populations (e.g., Depression, Alzheimer's disease, Huntington's disease, Korsakoff's disease, forms of learning impairments in children) and several types of psychoactive agents (cholinergic drugs, noradrenergic drugs, serotonergic drugs, drugs that alter GABA activity, neuropeptides), it has been possible to begin to define the psychobiological relationships between knowledge and episodic memory, encoding processes, effortful (active) cognitive operations as opposed to automatic cognitive processes and how retrieval processes are mediated by the context (state of central nervous activity).